Fixed 2 clippy warnings

Use String::push rather than String::push_str when dealing with text 1 in length

src/data.rs

@@ -596,7 +596,7 @@ impl Data {
                 } else {
                     out.push_str("Data");
                 }
-                out.push_str(">");
+                out.push('>');
                 out
             },
             Self::Map(m) => {
@@ -618,7 +618,7 @@ impl Data {
                 } else {
                     out.push_str("Data");
                 }
-                out.push_str(">");
+                out.push('>');
                 out
             },
         }